Using Intelligent Output Terminals
Operations
and Monitoring
4–24
Output Deviation for PID Control
The PID loop error is defined as the
magnitude (absolute value) of the differ-
ence between the Setpoint (target value)
and the Process Variable (actual value).
When the error magnitude exceeds the
preset value for C44, the [OD] terminal
signal turns on. Refer to the PID loop
section on page 4–33 for more on PID loop
operation.
NOTE: The example circuit in the table above drives a relay coil. Note the use of a diode
to prevent the negative-going turn-off spike generated by the coil from damaging the
inverter’s output transistor.
Process variable
C44
set
value
[OD]
Signal
time
Setpoint
rror
(SP-PV)
ON ON
C44
Option
Code
Terminal
Symbol
Function Name
Output
State
Description
04 OD Output deviation for
PID control
ON when PID error is more than the set threshold for
the deviation signal
OFF when PID error is less than the set threshold for
the deviation signal
Valid for outputs:
11, 12, AL0 – AL2
Required settings:
C44
Notes:
•
The default difference value is set to 3%. To change
this value, change parameter C44 (deviation level).
CM2
1112
FM
H OIO L
Example:
OD
RY
+
–
Inverter output
terminal circuit
See I/O specs on page 4–5.
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